There's no way around it, Battletoads is a tough game. Those three lives you get at the beginning of the game start to look insufficient pretty early on.

But, you can give yourself a slight edge.

At the 'press start' screen you can hold Down on the control pad + A + B and press Start. Then you'll have five Toads at your disposal instead of three.

And, yeah, this works for the Super NES version also.